In the case where, in the space above a supporting structure such as a fixed structure, an object to be supported (hereinafter referred to as a supported structure) is supported, suspension or cushion support devices are used in order to prevent direct transmission of vibration from the side of the fixed structure to the supported structure.
Further, suspension or cushion support devices are used also for preventing transmission of vibration generated from the supported structure directly to the fixed structure.
As a conventional support device of this kind, one in which compression coil spring is interposed between the supported structure and the supporting structure is known. However, this device in which a compression coil spring is used effectively absorbs vibrations transmitted in the one-dimensional direction in which the spring elongates and contracts and can produce a cushioning effect but cannot amply produce a cushioning effect with respect to vibrations in directions perpendicular to that direction, and further, it also cannot readily return the supported structure to the prescribed original position in space. There are devices of the air-spring type in which an air-pressure cylinder is used in place of a compression coil spring, but similarly as in a device using a compression coil spring, it merely absorbs only vibrations transmitted in the direction in which the air spring elongates and contracts, and, with respect to movements in directions perpendicular thereto, the supported structure is placed in an unstable state.
For solving these problems, there is a device in which coil springs are assembled in three-dimensional directions in order to intercept vibrations transmitted in the three-dimensional directions. However, a device of this kind has had drawbacks such as that the places of installation of the coil springs increase, whereby the construction becomes complicated, and, furthermore, it is difficult to cause the supported structure to return to its original position and to become stabilized.
Accordingly, an object of this invention is to provide a support device adapted to isolate a supported structure from the effects of vibrations extending in three-dimensional directions thereby to support stably the supported structure in the space above a supporting structure.
Further, another object of this invention is to provide a support device so adapted that an elastically supported structure readily returns to the original position and can readily maintain stability of the attitude.